user
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:
Select the correct words among the given options to fill the blanks below the sentence:

The great wall of china was build __________ to keep invaders out.

### Input:
Options: a) strongly, b) very strongly, c) powerfully, d) formidably

### Response:
assistant
d) formidably